14.04 - Broken `apt-get update`

I have a problem, that when running $sudo apt-get update, it get's stuck with something like this:

Ign https://apt.dockerproject.org ubuntu-trusty InRelease                      
Ign https://download.docker.com trusty InRelease                               
Err http://dl.google.com stable InRelease                                      

Err http://dl.google.com stable Release.gpg                                    

  Unable to connect to 10.11.55.xxx:3142:
Err http://security.ubuntu.com trusty-security InRelease                       

Err http://security.ubuntu.com trusty-security Release.gpg                     
  Unable to connect to 10.11.55.xxx:3142:
Err http://us.archive.ubuntu.com trusty InRelease                              

Err http://us.archive.ubuntu.com trusty-updates InRelease                      

Err http://us.archive.ubuntu.com trusty-backports InRelease


Err http://packages.cloud.google.com cloud-sdk-trusty InRelease

Err http://us.archive.ubuntu.com trusty Release.gpg
  Unable to connect to 10.11.55.xxx:3142:
Err http://packages.cloud.google.com cloud-sdk-trusty Release.gpg
  Unable to connect to 10.11.55.xxx:3142:
Err http://us.archive.ubuntu.com trusty-updates Release.gpg
  Unable to connect to 10.11.55.xxx:3142:
Err http://us.archive.ubuntu.com trusty-backports Release.gpg

  Unable to connect to 10.11.55.xxx:3142:

And it takes a really long time, to ultimately fail. I suspect is some network configuration (my IP used to be 10.11.55.YY, but moved to a different network).

I noticed the issue when trying to install docker, but I'm not really sure it had to do anything with this issue.

Any pointers on how to solve this problem?